III. On the nebulæ of Argo and Orion, and on the spectrum of Jupiter

Abstract

Among the following observations made with the great Melbourne telescope, the most important are those of η Argo; the spectrum of this star is crossed by bright lines . The mere fact of a bright-line spectrum is not very difficult to ascertain on a good night; for although from faintness of the light the phenomenon is necessarily delicate, yet the bright lines occasionally flash out so sharply that the character of the spectrum cannot be mistaken. The most mark lines I make out to he, if not coincident with, very near to C, D, b , f, and the principal, green nitrogen line. There are possibly other lines, but those mentioned are the only ones manageable.